Ferrocene polymers



nited States Patent "E 3,341,495

Patented Sept. 12, 1967 The same holds correspondingly for the positionof the su-bstituents R and R" in Formulae 11a and 11b.

These polymers are formed by two different methods, Eberhard NeuseSailta Momca asslgnor by as follows: (1) By polycondensation offerrocenyl carmesne assignments, to McDonnell Douglas Corporabin 018Such h d th 1 tion, Santa Monica, Calif., a corporation of Maryland 5 asy roxyme y errocene' No Drawing. Filed Sept. 12, 1963, Ser. No. 308,318

3,341,495 FERROCENE POLYMERS 5 Claims. (Cl. 26067) This inventionrelates to the preparation of ferrocene polymers.

In my copending application, Serial No. 233,913, filed October 29, 1962,now.U.S. Patent No. 3,238,185, entitled Ferrocene Polymers," I havedescribed the preparation of ferrocene polymers of the type:

(2) By polycondensation of N,N-dimethylaminomethylferrocene, or itsderivatives having the structural formula T l H ,CH Fe R2 ca Fe I n IaIV wherein R and R are H, CH phenyl, etc. Each wherein R is as definedabove.

polymer chain is believed to contain a double-bridged In accordancewiththe present invention a different segment either of the type 1121 orthe type IIb, below: type of ferrocene polymer .is prepared by differenttypes R 3 a. C C 1 CD R, 9 R 3 n I Fe 7 Y n R 0 [7 or R Ff R I a Ha I'Ibwherein R and R" represent polymer chains and R and R are H, CH C H orthe like. The centered position of the substituent link on the left-handside of Formula Ia is not to indicate direct bonding on the iron atom,but rather a mixed pattern of 1,2-hom0annular, 1,3-homoannular and1,l-heteroannular substitution as depicted by the three segmentstructure Ib below:

l, 1' -hetero i. L -b mQ of reaction. The polymers of the presentinvention have a repeating unit of the novolac type as follows:

wherein R and R are H, or alkyl groups such as methyl, ethyl, etc., oraryl groups such as phenyl or aralkyl groups such as benzyl,phenylethyl, etc. These polymer chains, in contrast to the previouslyclaimed polymers Ia, are lacking a double-bridged segment of the typesIla and 11b depicted above and can thus be represented by Formula VI:

In Formulae V and VI, as well as in others presented in the following,again the position of the substituent link on the left-hand side denotesa mixed substitution pattern of the type shown in Ib. It will also beunderstood that the cyclopentadienyl rings may be substituted, e.g., bylow molecular weight alkyl groups (e.g., methyl, ethyl,

etc.) or aryl groups (e.g. phenyl), or aralkyl groups (l) :1 Fe

err-N5 H Those polymers of type VI in which R and R are both hydrogenare especially useful because of their high Weight ratio of ferrocene tonon-ferrocene groupings, this ratio being about 13:1, corresponding to aferrocene content of 93%. These preferred polymers have the formula Theyare especially useful as components of rocket propellants (wherein theferrocene unit in the polymer has the function of a burning ratecontroller) because, per pound of polymer, there is a higher proportionof iron than in those polymers where one or more of the methylenehydrogens is subtituted by methyl, ethyl, or higher alkyl, aryl, oraralkyl groups. In those instances Where n has a value higher thanunity, polymer VII has additional utility for the stated purposebecause, in contrast to monomeric ferrocene, it is not volatile, henceis not lost and does not diffuse during processing of a rocketpropellant nor during storage, shipment or the preparation of a rocketfor firing. These polymers can be used to advantage in sealants,varnishes and laminates, particularly to impart heat stability. Thusthese polymers can be added to phenolic resins in the A stage to produceadhesives, potting agents and laminating agents, wherein the ferrocenylpolymers impart greater heat stability. Also, these polymers can be usedas substitutes (having much lower volatility) for ferrocene as catalystsin combustion reactions. A further use is as electron exchange agents,by reason of the reversible reaction Thus by passing a solution of areducible ion through a column of such polymer it can be reduced. Also,these polymers are effective absorbers of ultraviolet, nuclear and gammaradiation and can be used as protective coatings or layers on equipmentsubjected to such radiation. Also these polymers can be added to varioustransparent polymers to impart laser characteristics.

Polymers of the type VII above (R and R =H) can be prepared by either oftwo reactions, as follows:

In reaction (1), the condensation is carried out in the melt phase undernitrogen at atmospheric pressure, using as catalyst a combination of a'Lewis acid, preferably ZnCl but permissibly AlCl BF etc., and HCl, bothcomponents being in the stoichiometric ratio as indicated in theequation. Employing a molar excess of HCl over the stoichiometricamount, while resulting in substantially shortened reaction times, atthe same time leads to crosslinking and partial destruction of theferrocene molecule and, therefore, requires more careful control of thereaction conditions. In lieu of the HCl component, water can also beused; in this case, however, considerably higher concentrations of ZnClare required, the latter component furnishing HCl by partial hydrolysis.It has also been found that the catalyst components can be introduced inthe form of the addition complex, described in the aforesaid copendingapplication, of the amine IV, ZnCl and HCl, having the composition:

Using this complex, polycondensation with resulting formation of VII isachieved by simply heating it for a sufficiently long time in thepresence of ferrocene at temperatures well above the melting point,i.e., at 160-180". In still another approach, the hydrochloride ofN,N-dimethylaminomethylferrocene is heated with ZnCl and ferrocene,yielding the same polymer VII.

In reaction (2) and also in reaction (2a), in which formaldehydedimethylacetal (dimethoxymetha'ne) substituted for formaldehyde, Lewisacid catalysts, such as ZnCl or AlCl are used, but at lowerconcentrations, e.g., at 5-20% (by weight of ferrocenc), and thereaction is carried out in a closed system (sealed glass tubes orautoclave). Reaction (2a) is preferred. Under such conditions,temperature-dependent melt equilibria are attained, and the conversionsremain correspondingly low, i.e., in the range from 60 to 70% inautoclave reactions (with reactions conducted in sealed glass tubes,conversions are usually higher by approximately 5%). However,theunrecated ferrocene can be recovered to a major extent and re-used.At temperatures substantially exceeding 175-180, further increasedconversions (up to ca. 80%) are observed; however crosslinking becomesnoticeable and the polymers obtained tend to increasingly deviate incomposition from structure VH.

For further utilization of low molecular weight fractions stillcontaining unreacted ferrocene, they may be subjected to apost-condensation with formaldehyde or its acetal under comparableconditions resulting in further consumption of the ferrocene present,coupled with increased molecular weight of the condensation products.

The following specific examples will serve further to illustrate thepractice and advantages of the invention.

+ n HCHO +v1r :1 H2O n CH (OCH -7 VII nCH 0H Example I.C0ndensatzon ofN,N-dimethylaminomethylferrocene with ferr0cene(Reaction (1) Into a 200ml. round bottom flask equipped with mechanical stirrer and gas inletand outlet tubes was placed 15.0 g. (0.0622 mole) ofN,N-dimethylaminomethylferrocene (IV) and 4.30 g. (0.0312 mole) ofanhydrous zinc chloride of 99% purity. After flushing the system withdry nitrogen, 5.98 g. (0.0622 mole) of 38% aqueous hydrochloric acid wasadded with vigorous agitation. Under a steady stream of nitrogen, themixture was quickly heated in an oil-bath to (All temperatures arecentigraded.) Upon the addition of 2.32 g. (0.0126 mole) of ferrocene,the bath temperature was raised to Heating was continued at thistemperature with stirring for 7.5 hours, until the melt had becomehighly viscous and agglomerated around the stirrer blades, and the waterextract of a sample of the melt no longer exhibited a yellow color.

The cold, pulverized melt was exhaustively extracted with warm water toremove residual catalyst and ionic byproducts, and, after drying, wasdissolved in 300 ml. of benzene. The filtered solution was poured withvigorous stirring into 2 liters of isopropanol, and the precipitatedpolymer portion (referred to as the first fraction) was washed withisopropanol and dried for 10 days at 60 in vacuo, to give 8.96 grams(69.6% yield) of yellow-tan, fine-powdery solid exhibiting the meltingrange 130-155 and the number-average molecular weight (M,,) 3650.

Analysis.Calcd. for VII: C, 66.60; H, 5.10; Fe, 28.30. Found: C, 67.01;H, 5.13; Fe, 27.93. 7

From the combined mother-liquor and washing liquids, by concentrating toca. 400 ml. and precipitating with excess water, a further portionessentially consisting of oligomers and unreacted ferrocene wasisolated. Upon removal of the latter ingredient by vacuum sublimation orchromagtography on activated alumina, the residual solid, hereindesignated as second fraction, weighed 2.02 g. (13.0% yield) and showedthe melting range 70-85 "g M 850.

Analysis.-Calcd. for VII: C, 66.24; H, 5.16; Fe, 28.60. Found: C, 66.34;H, 5.31; Fe, 28.38.

The total polymer yield (combined first and second fractions) thusamounted to 82.6%.

The crude polymer may be purified chromatographically by passing itsconcentrated benzene solution through a short column packed with aluminaof a low degree of activity and eluting with the same solvent. Thisprocess serves the purpose of removing traces of admixed polymericoxidation products. However, with the polymer adsorptivity beingenhanced with increasing molecular weight, its use is unfeasible for thehigher members.

Further fractionation to more monodisperse subfractions with M valuesranging from ca. 400 to 15,000 may be achieved by fractionalprecipitation from benzene, using isopropanol and, at a later stage,aqueous isopropanol,

as the precipitants. Fine, powdery, yellow-to-tan solids are obtainablefrom these resinous subfractions by reprccipitation from concentrateddioxane solution into excess methanol or isopropanol (using 90% aqueousethanol 8 A mixture of 23.0 g. (0.0822 mole) ofN,N-dimethylaminomet-hylferrocene hydrochloride, 7.65 g. (0.0411 mole)of ferrocene and 5.67 g. (0.0411 mole) of 99% anhydrous zinc chloridewas well ground in a dry box and for the last fractions), then dryingseveral days in vacuo was placed into a 2 roundbottom flask equipped ata temperature 8 below the meltwg The Poly as in Example 1. The flask wasinserted into an oil-bath fi i thus 928 g? ig i E g pre-heated to 170,and stirring was started. Under a 0 g 1 g fi g g e m blanket of drynitrogen, heating was continued at this Wa er prac lea y so m ID a m a q0 6 q temperature for 6 hours. Workup was accomplished in tone andhexane. As the molecular weight decreases, mthe manner descrbed in Exam1e 1 to ive 1177 creased crystallinity and enhanced solubility inaliphatic 68 07 1d i fi t f p M d alcohols, hexane, ether, etc. isnoticeable. The range of M 0 yle 2 0 e 6 2 above stated (i.e., about 400to 15,000) corresponds to (1 z oft B sewn. fractlon 7 Wlt tota Polyvalues of n in Formula VI ranging from about 1 to about mer yleldamountmg to 783% 75. l5 The analytical data were as follows:

other examples in which the c1 1 I Anal-ysis.-Calcd; for VII (firstfraction): C, 66.56; H, tern was employed are summarized in Table I,stating re- 5-11'F011I1d2 H, action conditions, yields, and elementalcomposition data y for VII (Second 330110101 on the first fractions. H,5.17. Found: C, 66.09; H, 5.29.

TABLE I Catalyst Concentration 1 Anal. Calcd. for First Anal. Found onFirst Molar Ratio Compound Temp. Time Total Mu of Fraction FractionIV/Ferrocene 0.) (hrs) Polymer First Z1101: H01 H20 Yield Fraction 0 HFe' O H Fe 1 11 moles, for every mole of Compound IV. 2 Combined yieldof first and second fractions, in percent of theory. 3 Dioxane used inlieu of benzene as solvent. Example 2.C0ndensation ofN,N-dimethylaminometh- Example 4.-C0ndensati0n of ferrocene withformaldeylferrocene with ferr0cene(Reacti0n (1)) 35 hyde-(Reaction (2a))Empolying the same equipment as used in the preced- This exampleillustrates the use of the aldehydic coming example, the mixture of 5.0g. (0.0207 mole) of ponent in the form of its acetal. N,Ndimethylaminomethylferrocene (IV), 2.85 g. The reactor was astainless-steel lined, high-pressure (0.0207 mole) of 99% anhydrous zincchloride and 0.37 (5000 p.s.i.) autoclave of 1 liter capacity, equippedwith g. (0.0205 mole) of water was heated with stirring under mechanicalstirrer, thermometer well and thermocouple, nitrogen, until thetemperature had reached 160". Upon bleeding valve, and a special safetyhead (rupture disc the addition of 0.96 g. (0.0052 mole) of ferrocene,the tested to 3500 p.s.i.). A heater mantle with thermostatbathtemperature was raised to 170 and there maintained controlled powerinput provided for uniform heating of for 6 hours. The condensationproduct was worked up as the reactor walls. The vessel was flushed withdry nitrogen described in Example 1 to give 3.32 g. (77.3% yield) of andwas charged with the mixture of 372.1 g. (2.0 mole) the first fraction,melting range 125135, M 3700. of ferrocene and 18.6 g. (5% by weight ofthe ferrocene) Analysis.-Calcd. for VII: C, 66.60; H, 5.10; Fe, 28.30.of 99% anhydrous zinc chloride previously ground to- Found: C, 66.79; H,5.26;Fe, 28.25. gether in a dry box. The solid occupied about one-halfThe second fraction was obtained in 9.9% yield (0.51 the total internalvolume. Upon the addition of 183.0 g. g.),melting range -85 ,M 820. (2.4mole) of dimethoxymethane precooled to 0, the Analysis.--Calcd. for VII:C, 66.22; H, 5.17; Fe, 28.61. autoclave was quickly closed and bolted.Heat was then Found: C, 65.89; H, 5.28;Fe, 28.89. gradually applied soas to raise the internal temperature Total yield (first and secondfractions): 87.2%. Within 1.5 hours to 170:2. Heating was continued atOther condensations, in which the ZnCl --H O catalyst 55 this level for9 hours, the temperature being recorded on system was used, aresummarized in Table II. an x-y recorder. During the entire reactionperiod, the

TABLE II Catalyst Concen- Anal. Calcd. for First Fraction Anal. Found onFirst Fraction Molar Ratio Corntratlon 1 Temp. Time Total Mn of Firstpound IV/Ferro- 0.) (hrs) Polymer 2 Fraction cene Yield 0 H Fe O H FeZnClr H20 1 In moles, for every mole of Compound IV.

2 Combined yield of first and second fractions, in percent of theory.

9 Dioxane used in lieu of benzene as solvent.

Example 3.C0ndensation of N,N-dimethylamr'nomethylferrocene withferr0cene(Reacti0n (1)) This example illustrates a reaction carried outusing the hydrochloride of compound IV (R =H) in place of the individualcomponents, IV and HCl.

acetal with dissolved catalyst, was thoroughly digestedand washed withwater. The insoluble solid, after drying for 3 days'in vacuo over Pweighed 395 g. It was dissolved in 500 ml. of benzene. Thefilteredsolution, upon concentration to about 300 ml., was slowlystirred into 4 liters of isopropanol. The precipitated polymer portion,after reprecipitation in the same manner, was obtained as a yellow solidconstituting the first fraction. It was washed and dried as described inExample 1 to yield 159.6 g. (40.5%); melting range 115130, M',,, 2190.

Analysis.Calcd. for VII: C, 66.52; H, 1.12; Fe, 28.36. Found: C, 66.33;H, 5.19; Fe, 27.84.

The second fraction, after removal of 45.7 g. of intermixed ferrocene,weighed 79.1 g. (20.4% yield); melting range 100-105, M,,, 590.

Analysfs.-Calcd.,for VII: C, 66.02; H, 5.19. Found: C, 65.78; H, 5.33.

- Additional examples of polycondensations of ferrocene withformaldehyde, the latter component either used as such(paraformaldehyde) or as its dimethyl acetal, are summarized in TableIII. The same procedure was employed with paraformaldehyde except thatit was added in pulverized form and was ground with the ferrocene andcatalyst.

stream, it was combined with the main product to give a total of 43.7 g.(84.7%) of crude polymer. M,,, 1430.

Analysis.Calcd. for VI (R =H, R =C H C, 73.18; H, 5.18; Fe, 21.64.Found: C, 73.33;,H, 5.25.; Fe, 21.39.

When condensation was conducted at 80 and 100, instead of 120, thecondensations led to yellow-colored polymers with M (rounded-off meanvalues from several runs) 1100 and 1250, respectively. Typicalanalytical data are as follows:

For product with M,,, 1140- Analysis.Calcd.: C, 72.87; H, 5.19; Fe,21.94. Found: C, 73.01; H, 5.31; Fe, 21.76.

For product with M,,, 1270 Analysis.-Calcd.: C,.73.04; H, 5.19; Fe,21.77. Found: C, 72.91; H, 5.25; Fe, 21.60.

At 135 oil-bath temperature, the polymer obtained was of a light-tancolor. M 2300.

Analysis.Calcd.: C, 73.68; H, 5.17; Fe, 21.15. Found: C, 73.87; H, 5.31;Fe, 20.86.

In all cases, crude polymer yields ranged from 80 to 92%.

TABLE 111 Anal. Calcd. for First Anal. Found for First Molar Ratio ZnClgTemp. Time Total Mn of Fraction Fraction Fen'ocene/ Form of AldehydeConc. 0.) (hrs) Polymer First Aldehyde Yield 2 Fraction 0 H Fe 0 H Fe1:0.8 Dimethyl acetal 5 170 10 53. 7 860 66. 24 5. 16 28. 60 66. 27 5,1O 28. 51 1:1 dn 5 170 9 3 59. 5 1, 320 66.41 5. 13 28. 46 66. 63 5. 28.14 1:1 4 10 170 3 5 27. 1 3, 900 66. 61 5. 10 28. 29 66. 50 5. 38 26. 881; 5 170 9 65. 1 2, 250 66. 53 5. 12 28. 66. 63 5. 16 28. 08 1; 5 190 185 32. 2 3, 100 66. 58 5. 11 28. 31 67. 54 5. 38 26. 83 1; 10 5 130 6 55.6 2, 140 66. 52 5. 12 28. 36 66. 28 5. 18 28. 29 1; 4 5 130 4 5 20. 3 3,350 66. 59 5. 11 28. 30 67. 36 5. 33 26. 90 1 4 10 170 2 0 68. 13 5. 57B 25. 67 1; 10 170 6 80. 4 1, 870 66. 49 5.12 66. 33 5. 11

1 In percent b.w. of ierrocene.

3 Similar yield, Mn and composition with 15% ZnClr concentration and 6hrs. heating time.

4 Anhydrous A101 in lieu of ZIlClg.

5 In addition large portion of crosslinked polymer of similar elementalcomposition. 6 At higher temperatures change in composition of (soluble)polymer; in addition, formation of crosslinked matter. 7 Onlycrosslinked condensation product. Same reaction course with BF; ascatalyst, added as ethereate.

9 Analysis on crosslinked reaction product.

9 Molar ratio oligomer (M.I 780)/acetal in postcondensation experiment.

In percent b.w. of oligomer.

The condensation of ferrocene with benzaldehyde is illustrated by thefollowing typical experiment. The wellground mixture of 37.2 g. (0.2mole) of ferrocene and 3.72 g. of zinc chloride was placed into a 200ml. of round bottom flask equipped with mechanical stirrer and twoside-tubes attached to the upper part of the bulb. Upon the addition of21.2 g. (.02 mole) of benzaldehyde, the mixture was heated with stirringin an oil-bath adjusted to 120. Throughout the condensation, a slowcurrent of dry nitrogen was passed through the side-tubes. Theorange-brown liquid gradually turned homogeneous and viscous, allowingstrings to be drawn from the melt. Heating was discontinued after 10hours. At this point, the mass had completely resinified, renderingfurther stirring difiicult.

The solidified melt was ground and digested with water and cold methanolto remove catalyst and a small portion of unreacted ferrocene. Theorange-brown, powdery residue was dried in vacuo and taken up in 300 ml.of dimethyformamide. The filtered solution was poured dropwise and withvigorous agitation into the three-fold volume of 95% aqueous methanol toprecipitate the polymer as a yellow, fine-powdery solid, which was driedfor 7 days at 60 in vacuo; dry weight 39.9 g. By adding excess water tothe mother-liquor and allowing the formed precipitate to settle, a smallsecond crop of essentially oligomeric material was obtained. Afterremoval of contaminating ferrocene by sublimation at 70 in a nitrogenExample 6.-Condensati0n of ferrocene and acetaldehyde. Formation of VI(R =H, R =CH Employing the equipment and procedure of Example 4, 2.0moles of ferrocene and 2.0 moles of freshly distilled acetaldehyde werereacted with anhydrous zinc chloride (10% by weight of ferrocene).Heating time was 7 hours, the temperature being 160. The first polymerfraction, obtained in 30.5% yield by precipitation from benzenesolution, showed melting range to 115; M,,, 1230.

Analysis.-Calcd. for VI (R =H, R =CH C, 67.45; H, 5.66; Fe, 26.89.Found: C, 67.00; H, 5.77; Fe, 26.31.

The second fraction, melting range 90 to M 630, was collected in 27.3%yield.

Analysis.-Calcd. for VI (R =H, I =CH C, 66.92; H, 5.62; Fe, 27.46.Found: C, 67.03; H, 5.80; Fe, 27.16.

It will be apparent that, by substituting alkyl or aryl derivatives,homologues of ferrocene (e.g., methylferrocene, phenylferrocene or thevarious dimethylor diphenylferrocenes, etc.) and/or halogenated, e.g.,chlorinated ferrocenes and/ or by substituting other aldehydes inreaction 2 and/or by substituting homologues of compound IV wherein oneor both methylene hydrogens are substituted by alkyl (methyl, ethyl,etc.) groups, other polymers of the type VI can be prepared in the samemanner and in which the ferrocene nuclei are substituted and/ or R and Rare other than hydrogen.

It will, therefore, be apparent that novel and useful compounds andmethods of obtaining them have been provided.

1 1' I claim: 1. A polymeric mixture of molecules having the structurewherein n is a positive integer and R is selected from the groupconsisting of hydrogen and the methyl radical, such mixture consistingpredominantly of such molecules wherein n is substantially in excess ofunity, said mixture having a number average molecular weight of at least860.

2. The method of polymerizing ferrocene which comprises reacting (1)ferrocene with (2) a material selected from the group consisting offormaldehyde and acetalde hyde, said reaction being carried out byheating a mixture 12 of the reactants in the presence of aLewis acidcatalyst, such heating being carried out in the substantial absence of asolvent and in the melt phase.

3. The method of claim 2 wherein the reactants are employed in molarratios of approximately 1 mole of ferrocene to 0.5 to 2 mols of reactant(2); and wherein the Lewis acid catalyst is employed in the amount ofabout 5 to 20% of the weight of ferrocene. 4. The method of claim 3wherein the Lewis acid is UNITED STATES PATENTS 5/1955 Grahan 260-439OTHER REFERENCES Luttringhaus et 211.: Die Makromolekulare Chernie, V01.44-46, 1961, pp. 669 6s1.

SAMUEL H. BLECH, Primary Examiner.

MURRAY TILLMAN, Examiner.

1. A POLYMERIC MIXTURE OF MOLECULES HAVING THE STRUCTURE
 2. THE METHODOF POLYMERIZING FERROCENE WHICH COMPRISES REACTING (1) FERROCENE WITH(2) A MATERIAL SELECTED FROM THE GROUP CONSISTING OF FORMALDEHYDE ANDACETALDEHYDE, SAID REACTION BEING CARRIED OUT BY HEATING A MIXTURE OFTHE REACTANTS IN THE PRESENCE OF A LEWIS ACID CATALYST, SUCH HEATINGBEING CARRIED OUT IN THE SUBSTANTIAL ABSENCE OF A SOLVENT AND IN THEMELT PHASE.